Conventionally, a data communication network system in which a plurality of terminals perform frame transmission and reception through a transmission line has been used. For example, as typified by recently used vehicles, increase of electronic control units (ECUs) mounted in the vehicles leads to advance in networking for communication. For example, a CAN (Controller Area Network) has been used for control system network, and a LIN (Local Interconnect Network) has been used for a body system.
Further, such an in-vehicle LAN (Local Area Network) is required to accurately control transmission timing. In response to the demand, for example, a communication timing control method as disclosed in Patent Literature 1 is used.